[fix] correct security, session, statistics, table-and-view, transaction, and types statement doc errors (#3717)

## Summary

Fixes 28 small documentation issues across security, session,
statistics, table-and-view, transaction, and types SQL-statement docs.
Each item below is independent.

### security

- **CREATE-ENCRYPTKEY.md** — AES_DECRYPT example result-table had a
stray space inside the border row breaking alignment; corrected to a
continuous border.
- **CREATE-ENCRYPTKEY.md** — access-control Notes column was copy-pasted
from a user/role grant statement; rewritten to describe ADMIN_PRIV at
Global scope (this statement is global, not per-user-or-role).
- **CREATE-FILE.md** — an orphan `**<file_name>**` heading appeared
above the canonical `**1. \`<file_name>\`**`; removed the duplicate.
- **DROP-FILE.md** — informal heading `## grammar:` → `## Syntax`.
- **SHOW-FILE.md** — Return Value docs the column as `FileId`, but the
example output (and the engine) emit `Id`; Return Value aligned to
actual output.

### session

- **CLEAN-ALL-PROFILE.md** — access-control table said `GRANT_PRIV` on
DATABASE; this is a global admin statement → `ADMIN_PRIV` / Global.
- **KILL-QUERY.md** — same kind of wrong access-control privilege;
corrected to `ADMIN_PRIV` / Global with the usual note (killing one's
own queries requires no privilege).
- **PLAN-REPLAYER-DUMP.md** — result-table had a duplicated header row;
removed. Also an orphan ``` fence at end of file; removed.
- **PLAN-REPLAYER-PLAY.md** — full-width semicolons `；` in syntax /
example replaced with ASCII.
- **SET-VARIABLE.md** — the user-variable description and example used
`@@your_variable_name` (which is system-variable syntax); corrected to
`@your_variable_name`.
- **SHOW-VARIABLES.md** — privilege column listed `Any_PRIV`, which is
not a real Doris privilege; replaced with "N/A — no specific privilege
required".

### statistics

- **ANALYZE.md** — last code fence at EOF was unclosed; added closing
fence.
- **DROP-STATS.md** — heading `## ## Required Parameters` had a doubled
`##`; corrected.

### table-and-view

- **DIAGNOSE-TABLET.md** — one sentence said "not supported in the
compute-storage coupled mode" while the surrounding lines correctly say
the statement is for the coupled mode; corrected to "not supported in
the storage-computing separation mode".
- **SHOW-DATA.md** — result-table rows were corrupted with stray `=`
after the pipes; cleaned up so the table renders.
- **SHOW-REPLICA-DISTRIBUTION.md** — two Chinese section headings
(`查看表的副本分布`, `查看表的分区的副本分布`) inside the English doc translated to
English.
- **SHOW-TABLET-STORAGE-FORMAT.md** — the single Return Value table
merged two non-co-occurring output shapes (default vs `VERBOSE`); split
into two tables that match the actual two example outputs.
- **CANCEL-BUILD-INDEX.md** — Chinese `其中：` in English doc → `Where:`.
- **ALTER-TABLE-COLUMN.md** — a tip said "see example 8" but no example
8 exists; pointed at the correct earlier example.
- **ALTER-TABLE-COMMENT.md** — three `grammar：` markers (with full-width
colon) replaced with proper headings.
- **ALTER-TABLE-ROLLUP.md** — orphan empty `### ` heading and dangling
"4. Keywords" line replaced with a proper `## Keywords` section.
- **CANCEL-ALTER-TABLE.md** — removed a placeholder "4. Cancel ALTER
CLUSTER operation" with `(To be implemented...)` body (ALTER CLUSTER is
not a documented statement).
- **CREATE-TABLE.md** — a Plain code fence contained both range output
AND a full CREATE TABLE statement; split into a Plain block (range
output) and a sql block (CREATE TABLE).
- **DESC-TABLE.md** — last code fence at EOF was unclosed in current /
3.x / 4.x; added a closing fence. (v2.1 was already correct and was left
alone.)
- **SHOW-PARTITION.md** — result block was opened with ```sql; changed
to ```text.
- **SHOW-DYNAMIC-PARTITION-TABLES.md** — heading `## Syntax：`
(full-width colon) corrected; truncated `pecify` → `Specify`; in the
`StartOf` description, `1rd to 28rd` → `1st to 28th`.
- **SHOW-TABLE-ID.md** — `### Description` (h3) → `## Description` (h2).

### transaction

- **ROLLBACK.md** — heading `## Syntax（Syntax）` corrected to `##
Syntax`.

### types

- **SHOW-TYPECAST.md** — frontmatter `"language": "zh-CN"` in English
doc → `"en"`. Truncated frontmatter description completed.

## Test plan

- [ ] CI doc build passes
- [ ] Spot-check the affected pages render correctly (closed code
fences, table-border alignment, proper headings, no Chinese
punctuation/headings in English docs, corrected access-control notes)